Northern Prairie Wildlife Research Center
Waterfowl Communities in the Northern Plains
Redhead. -- The redhead achieves highest average densities in the parkland
of the Prairie Provinces and in the Prairie Pothole Region of the Dakotas, and
the stratum containing the Woodworth Study Area had average densities in the
highest quartile. Continental populations of redheads showed no trend over the
25-year period, whereas those at Woodworth increased markedly after the mid-1970s
(Fig. 11). The increased numbers of diving ducks and ruddy ducks in the Woodworth
Study Area, in contrast to declines continentally, may reflect an increase in
emergent vegetation in wetlands on the study area. These species most frequently
nest over water in such vegetation, which increased after several years once
grazing in the area had ceased. Dabbling ducks, on the other hand, ordinarily
nest in upland vegetation and their numbers therefore would not be affected
closely by the emergent vegetation.
Redhead numbers at Woodworth did not correspond very closely to those of
wetlands and this was similar to what was reported by Johnson and Grier (1988).
Although simple correlation coefficients with weather variables were not significant,
May precipitation entered the best regression equation.
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